After two years, bipedal robot takes steps outside

Mythical creatures have a tendency to sparkle in sunlight, but a walking robot that exists on the University’s campus was working on something far more impressive when it ventured out into the open air.

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MARLO, a bipedal robot, is helping researchers develop the science of leg locomotion for machines. Essentially, the goal of working with MARLO is to get robots to walk just as well as, if not better than, humans.

MARLO was designed and built by Jonathan Hurst, assistant engineering professor at Oregon State University, using funding provided by the Defense Advanced Research Project Agency, a program funded by the Department of Defense. MARLO is one of three robots created using Hurst’s ATRIAS principle, or “assume the robot is a sphere.” The other two robots are housed at Oregon State University and Carnegie Melon University.

For the past two years, Engineering Prof. Jessy Grizzle has led a team of University scientists on a quest to program MARLO in the best, most stable way possible. He said in the future, these robots could be used to assist in situations that might threaten human life.

Grizzle said robots like MARLO could play a critical role in recovering from natural disasters like the tsunami that hit Japan in 2011. The tsunami struck the Fukushima nuclear power plant and caused enormous damage and subsequent radiation leaks that proved too dangerous for humans to try to fix.

“We want machines to go into situations that are too dangerous for humans, or more dangerous than we’d want to be sending humans in to,” Grizzle said.

The team began their work with MABEL — an earlier and slightly more primitive version of MARLO — whose hips only moved forwards and backwards. This version of the robot could not provide its own lateral stabilization and was confined to walking or running in circles inside the lab attached to a boom.

MARLO, however, can walk in all directions attached only to a safety cable that prevents it from toppling over and breaking when it loses balance. This improved ability to balance allowed the team to take MARLO for a test run outside the lab. On one chilly day in early December, MARLO finally saw the light of day.

“We’d done the length of the lab 25 or 30 times, but these robots are eventually supposed to be able to go outside and handle real walking situations,” Grizzle said. “One Saturday morning we took a shot at it, and it almost worked.”

MARLO walked around for about two hours until a knee broke. It took roughly an hour of sanding and gluing to put the pieces back together, and another day for the glue to dry.

“We’re still rookies at working on this robot, but we’ll lick that problem soon,” Grizzle said.

Engineering graduate student Brian Buss said he was attracted to the project because of the way it attacks such a complex problem, and he appreciates the potential it has to help people.

He related programming MARLO to teaching a child how to walk.

“A child is born with limbs and muscles, but can’t walk until it learns how,” he said. “The programming part we’ve done consists of figuring out what to do with six motors and sensors that measures angles if the robot is leaning over.”

Buss said balance is a trickier thing to accomplish than most people realize. It’s not as simple as some may think; when compared to MARLO, humans have the advantage of nerves that detect pressure and tipping angles, eyes to see where they’re going and flexible ankles that can correct balance issues.

The team plans to install high-performance internal measuring units on MARLO to give the robot an even better sense of balance. Currently, devices at the ankles measure forces on the ground while others calculate the angle of the body. However, these devices aren’t foolproof and MARLO still trips over itself from time to time.

Jill Petkash, an orthotic and prosthetic technician at University Hospital, started working with the team last September to select prosthetic feet that would provide the robot with more stability. She ultimately helped fit MARLO with College Park’s Tribute model prosthetic. The company agreed to donate the feet to the project free of charge.

The Tribute Foot is designed for human amputees, giving MARLO a more human-like gait. In addition, a series of clamps and tubes that attach the feet to the end of the robot’s legs act as a sort of shin bone, and provide an increased range of motion even though the ankle is fixed with respect to the rest of the leg.

These clamps and tubes will also simplify the process of switching out prosthetic feet, should the team choose to do so.

“MARLO is a standard production prosthetic item, so if they wanted lighter weight or more high performance materials, they could easily do that by just using standard componentry,” Petkash said.

MARLO is a completely customized machine, and its creators are still working to come up with better designs. But even when the programming team works until the early hours of the morning, getting to test and perfect their ideas is just one enjoyable part of the job.

“The really fun days are when we have a particular design that we want to try, like a new idea for controlling or improving control of the robot,” Buss said. “It’s exciting to see the robot work and get people excited about it."